The measurement of a hysteresis characteristic of magnetic material is required in research and development of the magnetic material and magnetic parts that utilize the magnetic material (e.g., a transformer, a coil head, a magnetic recording medium and the like), quality controls for products, and process controls for manufacturing these elements. In addition, the measurement of the hysteresis characteristic of a magnetic material is also required in the design of products including magnetic parts, such as a power source, electrical circuit, VTR and so on.
A conventional apparatus for estimating the hysteresis characteristic of magnetic materials is disclosed by Yoshifumi Sakurai, "Magneto-Ceramics" pp 202-227, published 1980, by Ohm Company in Japan. In that apparatus a B-H characteristic of magnetic material is measured with an X-Y coil while vibrating the magnetic material. The magnetic material is evaluated using a D.C. magnetic field; therefore, if the magnetic material is to be used in a high frequency application, the hysteresis estimation for the magnetic material thus obtained will not represent a real or practical characteristic of the magnetic material. In addition, the apparatus requires an enormous yoke and thus its price is high.
A B-H analyzer for measuring a hysteresis characteristic of a magnetic material in a high frequency range is disclosed in "Nikkei Electronics" pp 300-311, published on Oct. 2, 1989 by Nikkei Business Publications Inc. in Japan. In that apparatus a magnetic material is magnetized by a high-frequency current flowing through a primary coil and a magnetic field H and a magnetic flux density B are estimated on the basis of the high-frequency current and an induced voltage produced across a secondary coil. However, this type of analyzer requires an expensive high-speed A/D converter and has the further disadvantage of a frequency band restricted to 10 Mhz or less. Generally, however, the magnetic field H and the magnetic flux density B include high-frequency components, which in this scheme are not detected. Thus, in this analyzer the actual hysteresis characteristic of the magnetic material cannot be accurately estimated.